8.1 Introduction

Until this point, this volume has described and explained the techniques and concepts involved in performing near-field antenna measurements in a systematic form. This was done by

• Addressing the fundamental phenomenological action of antennas.

• Developing a conceptual model of the interaction of antennas based on classical electromagnetic (EM) field theory.

• Deriving a methodology for the solution of the differential equations of classical EM field theory based on the plane wave spectrum approximation.

• Describing the details of a measurement technique (near-field scanning) that can be used to make measurements of the coupling between two antennas, the antenna under test (AUT) and a probe antenna.

• And finally making predictions of the far-field radiative performance of the AUT based on the plane wave spectrum approximation.

However, the problem of deriving the measure, that is, the true value of the magnitude of a physical quantity, like the power flux density transmitted in a given direction relative to an antenna, from measurements has not as yet been addressed. Note that this is strictly the primary measure of the measurand in question; other secondary measures can be derived from the measurement results but unless specifically stated, in this chapter measure will be taken to mean primary measure.

8.2 The Establishment of the Measure from the Measurement Results

The concept of measurement is interpreted differently in different sciences and therefore by definition in different areas of engineering and technology. As described in Chapter 1 the information extraction model is a particularly applicable concept for the...